It has been previously proposed to employ a two-level metalization technique to produce charge coupled devices. For example, in the application of Collins et al, Ser. No. 130,358, filed Apr. 1, 1971, (now U.S. Pat. No. 3,756,924 issued Sept. 4, 1973) entitled "Semiconductor Device and Method of Fabrication," and assigned to the assignee of the present application, a procedure is disclosed for fabrication of a charge-coupled device. Two-level metalization is employed. To anodize the first level metal, e.g., aluminum, a metal buss bar is used to interconnect all electrodes paterned in the first level. A voltage is applied through the buss bar to the electrodes, to partially anodize the electrodes and thereby provide an electrically insulated layer over them.
In the identified Collins et al application, since not all of the electrodes of the first level were to be electrically connected during operation of the device, it was necessary to remove the buss bar after the anodization step. The identified application of Collins et al. suggests removal of the buss bar by either anodizing it to completion or by etching it away.
It is, of course, desirable in fabricating semiconductor devices to use as few steps as possible, and to fabricate with the greatest reliability possible.
It is accordingly a feature of the present invention to provide a method of fabricating three-phase charge coupled devices having closely spaced electrodes, employing fewer steps than were previously required.
A further feature of the invention is to provide a method of fabricating such devices more reliably than was possible with previous techniques.
Other objects and advantages of the invention will be apparent to persons skilled in the art from a consideration of this specification, including the claims and the drawing.